Automated or robotic swimming pool cleaners traditionally contact and move about on the pool bottom and wall surfaces being cleaned on four axle-mounted wheels, resilient rollers that are transversely mounted at either end of the unit, or on endless tracks that are powered by a separate drive motor through a gear train to propel the robot over the surfaces of the pool that are to be cleaned. The water pump can drive a water turbine connected via a gear train to the wheels or endless track. Robotic swimming pool cleaners have a pump motor that powers a water pump that draws water through the moving unit and the moving water dislodges and/or “vacuums” debris up into a filter. The water pump can be internal or external to the robotic cleaner. The water exiting the unit having an internal pump in the form of a pressurized stream, or water jet can also be used to move the cleaning apparatus by reactive force.
Automated power-driven pool and tank cleaners are provided with pre-programmed solid state control devices to cause random and/or regular patterns of movement of the apparatus. The purpose of the programmed movement is to maximize the probability that the apparatus will cover the entire bottom and, optionally, the side wall surfaces during the cleaning operation in as little time as possible. An efficient cleaning pattern can also be selected based on the shape and size of the pool.
Often the bottom of a pool or tank has projections or an uneven surface. These obstacles can stop a robotic cleaner or delay the apparatus with much of the directional cycle spent with the apparatus immobilized or diverted from its intended path by a projecting obstacle or pool surface contour. In either case, this is an undesirable result because it lengthens the cleaning time and wastes externally provided electricity or the power of an on-board battery. Furthermore, the obstacle or contour can change the route of patterned travel of the apparatus, thereby reducing cleaning efficiency.
Prior art pool cleaners have addressed the problems of obstacles and extreme surface contours. One prior art method is to reverse and/or change direction of the apparatus when its intended forward movement is prevented. For example, U.S. Pat. No. 6,758,226 to Porat describes an automatic power-driven pool cleaning apparatus in which a motion translation member contacts the surface being cleaned and an associated signal transmitter and a motion sensor is connected to the pool cleaner's electronic control device. When the cleaner is moving, the motion results in a predetermined signal pattern and when the cleaner stops, the signal pattern is interrupted. After a predetermined period of time, the control device causes the cleaner's drive means to move the cleaner in a different direction. The obvious drawback is that the regular pattern of travel is changed thereby potentially reducing the efficiency of the cleaning apparatus.
Another solution to the problem of obstacles is to raise the baseplate by employing larger diameter wheels or supporting propulsion rollers, or by providing adjustable mounting means so that the user can change the distance between the underside of the baseplate and the pool surface depending upon the specific conditions present in the pool. However, pool cleaners remove dirt and debris from surfaces traversed by applying a suction force proximate to the surface to be cleaned to draw debris that rests on, or that is suspended close to the surface beneath the apparatus through openings in the baseplate and into a filter. The interior edge of the inlet opening is preferably near or on the longitudinal center axis running along the baseplate. Since the suction force diminishes rapidly with an increase in distance between the surface being cleaned and the baseplate inlet openings, merely raising the baseplate is not a practical solution to the problem of obstacles that project from the bottom or sidewall of the pool.
It would therefore be desirable to provide a method and apparatus for cleaning the bottom and side walls of pools and tanks that have projecting surface obstacles or extreme contours without stopping or significantly interrupting or altering the cleaning pattern of a self-propelled robotic cleaner.
It would also be desirable to provide a means for easily and economically increasing the suction force for existing pool cleaning apparatus in order to provide an improved degree of cleaning for different types of pool surfaces.